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本文针对滑动平台与动圈对接后水平横向振动系统的扫频试验的上限频率载止在400Hz的问题,对系统作了振动模态的有限元分析。在有限元分析中把所有离散化了的结构全部采用SAP5单元库中的平面应力膜元,这种膜元是改善了峦曲性能的威尔逊(wilson)不协调元,它很好地反映了本振动台系统的振动性态,这种膜元(与板壳元相比)大大地减少了自由度和带宽,从而节省了大量的计算费用。此外,还采用了SAP5程序中的边界元,用以提供油膜对滑台上有关节点的刚度,清除某些膜元上的非正向奇点以及用来模拟系统中的一些弹簧作用,也是较为成功的。本系统振动模态分析结果表明:激振动圈通过喇叭口部件以弯曲,扭转及(拉)压的形式向滑动平台传递激励力,也即此时激振动圈所发出的激励力大部份消耗在系统的弯曲和扭转振动,仅以部份的分量(拉或压)来驱动滑动平台的水平运动,这样势必导致激励能量大部份变为弯曲和扭转所做的功,从而使得扫描上限频率载止在400Hz左右,这与试验结果是一致的。
Aiming at the problem that the upper limit frequency of the frequency sweep test of the horizontal transverse vibration system after the butt joint between the sliding platform and the moving coil is stopped at 400Hz, the finite element analysis of the vibration mode of the system is made. In the finite element analysis, all the discretized structures are all based on the planar stress membrane element in the SAP5 cell library, which is a wilson incongruous element that improves the curvature of the curve. It reflects this The vibratory behavior of the shaker system, this type of membrane element (as compared with the plate shell element) greatly reduces the degree of freedom and the bandwidth, thus saving a lot of computational expense. In addition, the boundary element in the SAP5 program is also used to provide the stiffness of the oil film to the node on the slide, to clear the non-singular singularities on some elements and to simulate some spring effects in the system, successful. The vibration mode analysis results of the system show that the excitation dynamic force transmits the excitation force to the sliding platform in the form of bending, twisting and (pulling) pressure through the bell mouth component, that is, the excitation force generated by the excitation vibration coil consumes most of the time Bending and torsional vibrations in the system drive the horizontal movement of the sliding platform with only a fraction of the force (pull or pressure), which will inevitably result in most of the excitation energy becoming bending and twisting the work done so that the upper limit frequency of sweep Set to stop at about 400Hz, which is consistent with the test results.